BEIJING, April 29 (Reuters) - China said on Tuesday it would charge a former senior official and ally of China's retired security boss Zhou Yongkang after a Communist Party investigation found him guilty of taking bribes and engaging in "feudal and superstitious" activities.

Li Chuncheng was deputy party boss of the southerwestern province of Sichuan, and had for many years overseen development of the province's prosperous capital, Chengdu, until the party began investigating him for graft in late 2012.

Sichuan was Zhou's powerbase, where he served as party boss from 1999-2002. Li began working in Sichuan in 1998 and had worked there ever since, rising up through the ranks.

The party's anti-corruption body, in a brief statement, said that Li had been removed from his public post and expelled from the party.

"After an investigation, Li Chuncheng (was found to have) used the convenience of his position to seek benefit for others, and received a large amount of bribes," the statement said.

It added that his wife and daughter received "large amounts of goods" from other people, and that Li also abused his position to help his brother's business.

Li "misused his position to engage in feudal and superstitious activities, causing great financial losses for the state" and was "morally degenerate", the statement said, in language typically used by the party of corrupt officials.

It added that his acts constituted crimes, and he would be turned over to the judicial authorities for prosecution.

It was not possible to reach Li or his family members for comment and it was not clear if they have lawyers.

President Xi Jinping has launched a sweeping crackdown on corruption since taking power, warning corruption is a threat to the Communist Party's survival.

Sources have told Reuters that Zhou has been put under virtual house arrest, though the party has yet to make an announcement about his case.

Several of Zhou's political allies have been held in custody and questioned over corruption, including former Vice Minister of Public Security Li Dongsheng and Jiang Jiemin, who was the top regulator of state-owned enterprises for just five months until September.

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It is unclear if the government will put Zhou on trial and risk embarrassing public revelations about China's elite, potentially undermining confidence in the party.

Zhou was a patron of former high-flying politician Bo Xilai, who was jailed for life last September for corruption and abuse of power in the worst political scandal since the 1976 downfall of the Gang of Four led by the widow of former leader Mao Zedong at the end of the Cultural Revolution.

Zhou retired in 2012. He was last seen at an alumni celebration at the China University of Petroleum on Oct. 1 last year.

Separately, China's Supreme Court said on Tuesday that all cases involving early release or parole for officials sentenced for graft must be done in an open and transparent way, to prevent underhand means being used to secure lighter sentences. (Reporting by Ben Blanchard and Li Hui; Editing by Ron Popeski)